Netflix for Books?

One of the education blogs I read is the "Infinite Thinking Machine." The folks who post to this blog are educators and power users of technology, so there's always something useful on the blog. I was scrolling through the RSS feed I have set up for ITM and discovered this post on finding sites for kids to search and comment upon books, much like Netflix does for movies. I thought what Wes Fryer, the blogger, had to say about the three sites he's found was interesting. The comments that folks have left him were equally interesting. Have a look!